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Superconductor Week Speaks with Venkat Selvamanickam

31.03.2011

Superconductor Week spoke recently with Venkat Selvamanickam, Professor at the University of Houston (UH) and Chief Technology Advisor at SuperPower, regarding the process of transferring HTS and LTS technology into the grid. Selva was relocated from Schenectady, NY, along with SuperPower’s R&D division, to UH in 2009 under a research agreement between SuperPower and UH to collaborate on the development of SuperPower’s 2G wire (see Superconductor Week, Vol 23, No 18).

Selva is heavily involved with the Applied Research Hub (ARH) at the Texas Center for Superconductivity at UH (TcSUH). ARH was established to provide new infrastructure and capabilities for applied research and to attract companies to engage in collaborative R&D. There are currently two primary fields of research at the ARH: wire development, which involves industrial partners such as SuperPower and Bruker, and biomedical initiatives, superconducting quantum interference device (SQUID) including partners like Baylor College of Medicine,Methodist Hospital, the M.D. Anderson Cancer Center and the University of Texas’s Health Science Center.

“Through our partnership we have developed improved wire that can operate at high magnetic fields, roughly two times better than previous wires. This wire has been transferred to SuperPower’s production line in Schenectady. We are seeking to improve the magnetic field tolerance and current carrying capacity of the wires we work on, and focus on materials that lend themselves to high volume production without much capital investment.

Last year, ARH was awarded a $3.5 million ETF grant by the State of Texas intended as seed money to finance expansion. In particular, the money helped fund two new faculty positions and UH’s acquisition of a business park “We are already involved in a couple R&D projects focused on superconducting fault current limiters (SFCL) and superconducting magnetic energy storage (SMES) devices.

“Two technologies we will be looking at are portable tapes and roll-to-roll processing, as we feel they could be of benefit in other applications. I project that in 3 to 5 years we will see more technology originally designed for superconducting wires being applied to some other fabrication constant. We are setting up a metal organic chemical vapor deposition (MOCVD) system at ARH, not only for superconductor but also semiconductor roll-to-roll processing.”

Selva said that technological advancements over the last 20 years had surpassed market penetration:

“There has been tremendous progress on superconducting technology, materials science, processing, and cabling over the last 20 years. “However, market penetration has lagged, and this is largely due to the conservative nature of the utility companies.

“However, over the last 5 years people have started to understand that there are some areas where superconductivity can be adopted faster, and these are the areas to focus on. Examples include high magnetic field, renewable energy, alternative energy and energy storage applications.

“Another reason for optimism is that 2G wire has only been available over the last 3 years or so. It’s remarkable how challenging material processing has been, it has taken us quite awhile to get to the stage where we can make HTS tapes in kilometer lengths. Our biggest challenge remains making the wire cost competitive.
Selva said SFCL technology had also been stalled by the conservative nature of utility companies: “SFCL technology was seen early-on as an opportunity for superconductors because there are not many equivalent devices available. However, the technology has been stalled by conservatism on the part of utility companies. In my own informal conversations with people involved in the electric grid but not part of the superconductivity community, I’ve found universal interest in SFCLs, they’re something people want to have.

“There is a DOE-funded project at ARH involving SuperPower,Waukesha Electric and Oak Ridge National Lab (ORNL) to develop SFCLs that are coupled to large-scale transformers, and this may be the wave of the future. The project doesn’t deal with the SFCL as a stand-alone device, but incorporates it as a bonus feature into another device that utilities need anyway. One benefit to this configuration is that you can get rid of oil in the transformer, which can cause fires.
“Looking at the next couple decades, I see applications in the energy and renewable energy markets, and in particular wind energy, representing a big opportunity for HTS. The ability to build wind turbines rated at 10 MW and greater using HTS generators is very attractive to a lot of companies, and this is especially true when dealing with offshore turbines.

“Energy storage is another big opportunity, as the DOE is investing in developing energy storage methods for solar and wind energy. There isn’t one single technology that is applicable for storage over the entire time spectrum of what is needed, whether it’s storage for a few seconds, a few “If we can create a SMES prototype that is a highly effective and efficient storage device and that has the ability to store things for a fairly long time, at least one or two cycles without

degradation. Under the current SMES project involving ARH, we’re dealing with a 30 T magnet operating at 4.2 K, so we’re really pushing the limits of the wire, and of course the price-performance remains a big issue.

“Maintaining a high Ic at the 30 T range is a challenge, and the AC losses are also a factor we are working on. We are currently mainly involved in the wire side of SMES development, and the potential is there for making wire for SMES.”

Selva said there was still plenty of room to improve YBCO tapes: “With regard to SMES, I still believe that the 2G YBCO-based materials are our best bet. On the performance side, we know that they are definitely superior to many other materials, and the beauty of the 2G wire is that there is still a lot of room for improvement. Improvements on the wire side for some of the other materials have not been all that impressive over the last few years, whereas improvements have been and are still being made on the YBCO tapes “Bi-2212 is a material that can be made into a round wire form, which is very attractive, and some of the work aimed at high field applications at low temperatures is promising. Not much time has been spent focusing on high field, low temperature applications, and on wire development for that.

The DOE labs in general have tended to focus on HTS at low to medium fields.

“What we are looking to research here is operations at 30 K, 40 K and maybe at 4.2 T, where we can really push the materials even farther, and there are still opportunities to do that with a number of materials, including MgB2. YBCO material is already really good, and the potential for further improvements remains high, especially if we look at improving its characteristics at low temperatures and high fields.”